Eiko t8 led typeB

gar

Senior Member
180427-2131 EDT

Mparn:

My two bulb experiment is not as good as I would like. The high current pulse generated by randomly turning on an incandescent (I used 75 W for convenience) does not have an adequately high probability of having its maximum value and longest duration as compared with a controlled turn on at the voltage peak. I could barely detect the transient pulse compared to the steady state change.

For an illustration of incandescent turn on current see my photos P1 thru P4 at http://beta-a2.com/EE-photos.html .

In doing this experiment the bulb being turned on should be totally out of view. Do not look directly at the always on bulb. Shine it on a wall or use something to greatly attenuate the brightness.

Do not view what I am describing as over your head. Think about it and ask any questions. You seem to have a great interest for looking into why things you see occur.

.
 

gar

Senior Member
180428-1146 EDT

Mparn:

I would like you to run an experimebt if you can.

I took my only LED fixture, a 4 ft twin tube Costco shop light, and with a Powerstat (variac) adjusted the input voltage from 70 to 140 V with a GE light meter monitoring the light intrnsity and saw virtually no intenity variation.

Do you have any way to change the AC sine wave voltage to one of your fixtures? If so, then even a visual observation may tell us whether the light output is particularly sensitive to voltage.

In contrast I can take a Cree screw-in 9.5 W bulb and get good dimming control with a variable sine wave voltage source.

.
 

Kinexis

Member
Location
Ohio
i recommend trying the new led's in various parts of the building's for a period of time (honestly i would test for a year before replacing that many) before replacing everything with LED, there has recently been an article series in EC&M magazine about ground planes for LED drivers that talks about some of the issues coming up with LED's especially in older facilities. i would think you would have decent bonding throughout the buildings but i would test before committing to all LED. i have seen several facilities that have kept replacing LED's and i suspect it may be related to the issue discussed in the articles in EC&M, they were older facilities and not very well wired to begin with.
 

Kinexis

Member
Location
Ohio
i'm not finding anyone else addressing it in this forum, but there was discussion over concern of 277v at the tombstones, don't most fixtures like the op currently has have lamp start voltages of several hundred volts at the tombstones? when you install or remove a lamp on an energized fixture you are exposed to that voltage, your exposed when you remove because you can easily disconnect and accidentally reconnect. or is the secondary of most ballasts not grounded?
 

Mparn

Member
Location
Missouri
Our building were built in 1988 and 1999. Thanks for the info on the magazine, I'll look into that.

Kinexis, are you concerned with 277 at the sockets?
 

gar

Senior Member
180429-2206 EDT

LarryFine:

For a cold cathode tube, mono end electrodes, it takes a relatively high voltage, 600 to 1000 V, to initiate ionization of the gas. After initiation of ionization, then the arc voltage drop is relatively low. The power source to the tube must be of a current limiting nature. High leakage inductance in the transformer.

Once a tube has been initiated the mono electrodes become fairly hot from tube current and the initial breakdown voltage per half cycle becomes less.

In tubes with two pins per end and a small heater electrode at each end, the earliest fluorescents, a preheat circuit including what was called starter was used to lower the initial breakdown voltage.

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LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
In tubes with two pins per end and a small heater electrode at each end, the earliest fluorescents, a preheat circuit including what was called starter was used to lower the initial breakdown voltage.
I have plenty of experience with starter-equipped fluorescent lights, and even have modified them with momentary switches to eliminate the starter. N.O. push-buttons to start the lights, and N.C. to extinguish them.

I've been doing electrical work for fifty or so years. I'll be 63 next month, and I did my first service upgrade when I was 15. I added a generator and T/S years later, and critiqued my own work. Proud to say I did everything correctly. :p
 

Kinexis

Member
Location
Ohio
Our building were built in 1988 and 1999. Thanks for the info on the magazine, I'll look into that.

Kinexis, are you concerned with 277 at the sockets?

no, i would put warning stickers on them though. say something like "DANGER 277Volts at tombstones, site policy is to de-energize light before servicing", or "De-energize or light will be damaged when servicing".

and also make sure everything is rated for it, the wire may be good at the high voltage only for start-up and not for continuous operation at the voltage i don't know though, just throwing it out there because i would look into it if i was going to do that

i always thought you should de-energize a light when changing lamps anyways, when you put it in unless you do it perfectly you can connect and disconnect and then reconnect which i think is very hard on lamps of any kind especially new ones. plus there hot and you might be more likely to drop it.
 

Mparn

Member
Location
Missouri
Update on our project.

Starting in February and completing in July, we have replaced approx. 5,000 lamps and decamped around 2,000. I know its early but here are some notes from the project.

Everyone seems to like the overall quality, consistancy, and level of lighting. It seemed a little bright for some at first, most of those rooms had several lamps out.

We've had a few issues; 1 lamp went bad, 2 lamps where the wire came loose, and 1 lamp was not put in correctly.

Our district has avgerged around 1.6 mil kWh per year over the last 3 years. We are on pace to end the year at 1.2 mill kWh. That should be around $40,000 in savings. I also adjusted the summer HVAC schedule, which also played a role in reduction.

Over the next month I will be replacing the exterior lighting. This includes; shoeboxes, flood lights, and wall packs. Each exterior fixture will have it's own surge protector.
 
Is there an update to this project? I work for a large school district and one of our new electricians ordered a lot of tombstone kits and type B lamps. We have never done type B lamps due to the mains voltage at the tombstone (non qualified personnel routinely are in the fixtures). Has this ever been a liability concern, safety issue or as a code issue and are we violating the UL listing by modifying the fixture with separate components vs a kit? Any input would greatly appreciated before we change direction in our retrofit program.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
The first thing I want to know is why there are unqualified people opening these fixtures?

Most kits that I have seen come with stickers that need to be installed but these are 120v units.
 
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